When you make a baby, half of the genetic information comes from the mom and half from the dad, right? Turns out, not exactly. Research from the emerging field of epigenetics, or outside factors that influence genes, shows that info in the mother’s egg plays a crucial role in the development of the placenta—and, therefore, in the health of the pregnancy. The findings, published in the journal Developmental Cell, could have implications for the importance of mom’s age and health even before conception.
More than just DNA
Using mice, researchers explored how the epigenetic process of turning genes “on” or “off” in the egg affects the development of the placenta’s cells after an embryo is formed. “We wanted to understand how epigenetic ‘marks’ inherited from the egg contributed to placental development,” lead author Miguel Branco, Ph.D., a senior lecturer at Queen Mary University of London, tells Fit Pregnancy. “We used mice where we could ‘erase’ this epigenetic information from the egg and then analyze the placenta during pregnancy.” Scientists already knew that the egg’s epigenetic info controlled a small number of specific genes, but this study proved that the scope of the egg’s influence is much greater than that.
Because of the egg’s ability to mark genes to be turned on or off, it has a lot of control over early pregnancy. “One of the ways by which epigenetics works is through small ‘tags’ or marks that are placed on the DNA to signal the cell to shut down a gene,” Branco says. “If epigenetic marks are not in the right places during the development of the placenta, this could affect its growth and the establishment of the different cell types that perform essential functions, such as attachment to the uterus or the exchange of nutrients between mother and fetus.” So, he says, “defects in the egg can have consequences for the development of the placenta and fetus.”
The eggs have it
Is there anything you can do to improve how your eggs mark your genes? Scientists don’t quite know yet, but it is possible that factors like your diet and age could have an effect. “Environmental factors certainly have the potential to alter a cell’s epigenetic information,” Branco says. “But more research is needed in this area. I don’t think we can yet pinpoint very well specific factors or nutrients that affect egg quality through epigenetics. However, folate [folic acid] is a good candidate, which, if proven, would further strengthen the case for folate supplementation even before pregnancy.” Folic acid helps with cell growth, so remember to take prenatal vitamins that contain folic acid if you’re trying to get pregnant.
As for age, this study could lead to ways to actually slow down mom’s biological clock. “It is still not quite clear how egg quality deteriorates with aging, but we do know that epigenetic information within our cells changes as we age,” Branco says. So, he says, it’s possible that such changes reduce fertility. But, “the great thing about epigenetic alterations is that they are reversible, so there is a real possibility of an ‘epigenetic treatment’ being developed in the future,” Branco says. More research is needed, but this study holds promise for understanding how healthy pregnancies develop, and how we might be able to improve a woman’s chances of becoming a mom at a later age.